1555 	 * Allocate NVMe PRP Pages for NVMe SGL support only if the FW supports  in mpr_alloc_requests()
1634 	 * 1 PRP entry in main frame for PRP list pointer still leaves 255 PRPs  in mpr_alloc_nvme_prp_pages()
1659 		mpr_dprint(sc, MPR_ERROR, "Cannot allocate NVMe PRP DMA "  in mpr_alloc_nvme_prp_pages()
1665 		mpr_dprint(sc, MPR_ERROR, "Cannot allocate NVMe PRP memory\n");  in mpr_alloc_nvme_prp_pages()
1951 	    &sc->prp_pages_free, 0, "number of free PRP pages");  in mpr_setup_sysctl()
1955 	    &sc->prp_pages_free_lowwater, 0,"lowest number of free PRP pages");  in mpr_setup_sysctl()
1959 	    &sc->prp_page_alloc_fail, "PRP page allocation failures");  in mpr_setup_sysctl()
2872 * native SGL (NVMe PRP). The native SGL is built starting in the first PRP entry
2876 * using the two PRP entriess inside the NVMe message, then PRP1 describes the
2877 * first data memory segment, and PRP2 contains a pointer to a PRP list located
2878 * elsewhere in memory to describe the remaining data memory segments. The PRP
2881 * The native SGL for NVMe devices is a Physical Region Page (PRP). A PRP
2882 * consists of a list of PRP entries to describe a number of noncontigous
2886 * non-contiguous SGL into a PRP in this case. All PRPs will describe contiguous
2889 * Each NVMe message contains two PRP entries. The first (PRP1) either contains
2890 * a PRP list pointer or a PRP element, depending upon the command. PRP2 contains
2891 * the second PRP element if the memory being described fits within 2 PRP
2892 * entries, or a PRP list pointer if the PRP spans more than two entries.
2894 * A PRP list pointer contains the address of a PRP list, structured as a linear
2895 * array of PRP entries. Each PRP entry in this list describes a segment of
2898 * Each 64-bit PRP entry comprises an address and an offset field. The address
2901 * first element in a PRP list may contain a non-zero offest, implying that all
2904 * Each PRP element normally describes a chunck of PAGE_SIZE physical memory,
2907 * then the first PRP element will contain a non-zero offset indicating where the
2910 * described by the PRP list. 
2912 * Since PRP entries lack any indication of size, the overall data buffer length
2914 * how many PRP entries are required to describe it.
2933 	 * without constructing any PRP.  in mpr_build_nvme_prp()
2941 	 * set the current PRP entry pointer to PRP1.  in mpr_build_nvme_prp()
2950 	 * For the PRP entries, use the specially allocated buffer of  in mpr_build_nvme_prp()
2951 	 * contiguous memory. PRP Page allocation failures should not happen  in mpr_build_nvme_prp()
2952 	 * because there should be enough PRP page buffers to account for the  in mpr_build_nvme_prp()
2956 	KASSERT(prp_page_info != NULL, ("%s: There are no PRP Pages left to be "  in mpr_build_nvme_prp()
2962 	 * Insert the allocated PRP page into the command's PRP page list. This  in mpr_build_nvme_prp()
2969 	 * first entry to be a PRP List entry.  in mpr_build_nvme_prp()
2983 	 * Set PRP physical pointer, which initially points to the current PRP  in mpr_build_nvme_prp()
3007 			 * This is the last entry in a PRP List, so we need to  in mpr_build_nvme_prp()
3008 			 * put a PRP list pointer here. What this does is:  in mpr_build_nvme_prp()
3011 			 *   - set the PRP Entry to point to that page. This is  in mpr_build_nvme_prp()
3012 			 *     now the PRP List pointer.  in mpr_build_nvme_prp()
3013 			 *   - bump the PRP Entry pointer the start of the next  in mpr_build_nvme_prp()
3014 			 *     page. Since all of this PRP memory is contiguous,  in mpr_build_nvme_prp()
3031 			 * Must fill in the first PRP pointer (PRP1) before  in mpr_build_nvme_prp()
3037 			 * Now point to the second PRP entry within the  in mpr_build_nvme_prp()
3045 			 * Should the PRP2 entry be a PRP List pointer or just a  in mpr_build_nvme_prp()
3046 			 * regular PRP pointer? If there is more than one more  in mpr_build_nvme_prp()
3047 			 * page of data, must use a PRP List pointer.  in mpr_build_nvme_prp()
3052 				 * PRP2 will contain a PRP List pointer because  in mpr_build_nvme_prp()
3053 				 * more PRP's are needed with this command. The  in mpr_build_nvme_prp()
3062 				 * The next PRP Entry will be the start of the  in mpr_build_nvme_prp()
3063 				 * first PRP List.  in mpr_build_nvme_prp()
3070 				 * After this, the PRP Entries are complete.  in mpr_build_nvme_prp()
3071 				 * This command uses 2 PRP's and no PRP list.  in mpr_build_nvme_prp()
3082 			 * all remaining PRP entries in a PRP List, one per each  in mpr_build_nvme_prp()
3159 		 * NVMe uses one PRP for each physical page (or part of physical  in mpr_check_pcie_native_sgl()
3182 			 * beyond end of the 5th page, we need the extra PRP  in mpr_check_pcie_native_sgl()
3222 	 * For the PRP entries, use the specially allocated buffer of  in mpr_check_pcie_native_sgl()
3223 	 * contiguous memory. PRP Page allocation failures should not happen  in mpr_check_pcie_native_sgl()
3224 	 * because there should be enough PRP page buffers to account for the  in mpr_check_pcie_native_sgl()
3228 	KASSERT(prp_page_info != NULL, ("%s: There are no PRP Pages left to be "  in mpr_check_pcie_native_sgl()
3234 	 * Insert the allocated PRP page into the command's PRP page list. This  in mpr_check_pcie_native_sgl()
3241 	 * first entry to be a PRP List entry.  in mpr_check_pcie_native_sgl()
3267 	 * NVMe has a very convoluted PRP format. One PRP is required for each  in mpr_check_pcie_native_sgl()
3270 	 * a PRP list pointer entry as the last entry in each physical page of  in mpr_check_pcie_native_sgl()
3271 	 * the PRP list.  in mpr_check_pcie_native_sgl()
3273 	 * NOTE: The first PRP "entry" is actually placed in the first SGL entry  in mpr_check_pcie_native_sgl()
3275 	 * message is the chain element, and the rest of the PRP entries are  in mpr_check_pcie_native_sgl()
3322 				 * Need to put a PRP list pointer here.  in mpr_check_pcie_native_sgl()
3348 				/* No longer the first PRP entry. */  in mpr_check_pcie_native_sgl()